Recuperator system for airplane cannons



June 14, 1949. H. N. METZEL 2,473,211

RECUPERATOR SYSTEM FOR AIRPLANE CANNONS Filed Sept. 14, 1945 4 Sheets-Sheet 1 P "I S 1 as ea 39 .3 a6

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June 14, 1949. H. N. METZEL 1 I 2,473,211

RECUPERATOR SYSTEM FOR AIRPLANE CANNONS Filed Sept. 14. 1945 4 Sheets-Sheet 2 Hnr 0111 N. Mai: 21

June 14, 1949. H. N. METZEL RECUPERATOR SYSTEM FOR AIRPLANE CANNONS 4 Shets-Sheet :5

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H. N. METZEL RECUPERATOR SYSTEM FOR AIRPLANE CANNQNS June 14, 1949.

4 Sheets-Sheet 4 Filed Sept. 14. 1945 arm W Patented June 14, 1949 RECUPERATOR SYSTEM FOR AIRPLANE. CANNON S Harold N. Metzel, East Lansing; Micha, assignor to General MotorsCorporation, Detroit, Mich., a corporation of. Delaware Application September 14, 1945, SerialNo; 616,329-

2 Claims.

This invention relates to; a recuperator for:

airplane cannon.

In mounting a cannon in anairplane, it is not always possible to place the cannon with the trunnions in a horizontal position. Sometimes 5 Fig. 1 comprises arr hydraulic cylinder 31, :a; plu the: cannon must be tilted or turned slightly 1 rality of sockets 33-: connected. to cylinder 31 by its axis to make it-fit or seat p perly in the gun passages 3d, and an expansion. chamber 32 conmount. stru'cted to be selectively assembled in any socket The recuperator system usually provided on the 33. An orifice. 35 for filling hydraulic cylinder 37 mm; Automatic Gun M; 9 or'like cannon gen- 10 3! is provided adjacent. each socket 33 and. aly' as an expansion ch be Which u bleeder passage 3819 provided in each socket:33l of the location of the recuperator cylinder imfor bleeding, together with means for sealing; mediately' below the barrel, isofiset with respect the orifice and passage 35 and- 36 respectively; to the vertical axis of the gun, with the result Spare plugs- 39. are provided for sealing the lllI- that when the gun is tilt mounted, the chamber used socketsgs y Comeon the lowv side. In this case, when The schematic structure above described is arr-- fil 'n 0 r p s g the O l pply in the reranged so that there will be a socket 331 for asc perator. system, t ec pansion chamber might semblyof the expansion chamber 32' above the become filled with oil instead of'air or conversely, 1eve1 of the cylinders, a connecting passage 34 s m air mi ht t into the yl nd r spl in 2o loading thereto. from the upper portion of the oil that should bend it; cylinder, and a. bleeder passage 36 leading: In order' to guard againstthiscontingency; it through socket. 33 into the lower partof the isthe'purpose ofthis inventiontov provide means chamber when the cylinder 3|. is rotatedto any for assuring that when the; recuperator system position up to sixty degrees each side of the isfi-lledor. replenished, air does not get into the vertical. cylinderandthat a substantially'uniform volume: A specific application of this invention is ilairpocket: is: retained in the expansion chamber. lustrated in Figs. 2 through 7 in which an hy- Accordinglyit: is the object of thisinvention drauli'c cylinder I, of the type utilized in auto-- to; provide, inconnection. with a recuperator sysmatic cannon is provided with diametrically optem, alternate means; for assembly of a detachposed integral lugs 3 at the forward end of cylable. expansion chamber, whereby such chamber" inder 8, each lug being provided with two bolt may bc -attached ina position that will assure holes 4 (Fig. 3). InZE-igs. 4 and 5. the. cylinder 1 n r pm nt f air within he: expansion chamis shown in they horizontal position and in Figs. her and preclude any airbeingv retained in the 6 and '7 in angular position with a gun barrel recoil cylinder. 2, in phantom. A top yoke 5 is assembled on The specifienature of the invention as well cylinder I, adjacent lugs 3 and is provided with as Ot er objects and; advantages thereof will bolt holes 6 matching holes 4 in lugs 3. A botclearly appear from a description. of a preferred tom yoke T with matchin bolt holes 8 is proembodiment as shown in the accompanying vided and bothyokesare secured in assembly drawingsin which: 40 o cylinder I by means of bolts 9. Screws Ill Fig. 1 is a schematicview of a generalized apare provided for added security in holding yoke 'plication of this invention to any hydrauli cyl- 5 in exact. location tightly against cylinder I. inder; Two integral protuberances l2 extendupward Fig. 2 is a plan view of a particular application ly and outwardly from each side of yoke 55 in a ofthis, invention, namely, the recuperator cylplane perpendicular to the; axis of cylinder I. inder of an automatic cannon; Each protuberance; I2: and the wall of cylinder Fig. 3 is a perspective view of one end of the l adjacent thereto is provided with an aperture recuperator of Fig. 2 shown with the end cap-reor passage l3 extending from the inside of cylmoved; inder I up and out through the top of protuber- Eig..4 is a sectional View of Fig. 2 taken along ance l2. A. removable: plug [4 is provided. for

theplane.44 thereof;

Fig.5"is a. sectional view of Fig. 2 taken along the plane 5-5 thereof;

Fig. 6 is a view similar to Fig. 4 but showing the. recuperator in a: tilted position; and.

Fig. 7 is: a view similar to Fig. 5 but-showing the. recuperatorl in the. same tilted position; as:

Fig. 6.

The invention as illustrated schematically in sealing the passage. [3.

a filler hole for introducing hydraulic fluid-into the. recoilsystem.

Each protuberance I12. terminates in a receptacleor Socket l1- opening rearwardly and somepassage serves as what upwardly and is provided with an inside threaded recess 18. An expansion chamber l9, preferably comprising a hollow cylinder, is provided for selective threadable assembly in either socket as desired and a plug 20 is provided for sealing the other socket.

Each protuberance I2 is provided with three apertures or passages, the first being the filler passage 13 described above. The second passage 2| extends from the bottom inside of socket ll to the upper part of cylinder I as shown in Fig. 2. The third passage 22 extends horizontally forward from a point near the top inside of socket H. A plug 23 is provided to seal each passage 22, which passage will hereafter be referred to as the bleeder, its purpose being to drain ofi the excess of hydraulic fluid when the system isfilled.

An airplane cannon is of course preferably installed with the trunnions horizontal, but this is not always possible. If the mounting is horizontal, expansion chamber I9 can be assembled in either socket, but if it is tilted toward one side then the chamber is assembled in the socket on the high side and plug 2| is used to seal the other socket. Plugs l4 and 23 in the same side as the air chamber are then removed and buffer oil is introduced through passage I3, filling cylinder I and then rising through passage 2! into expansion chamber [9 until it reaches the level of bleeder 22. Any excess of fluid beyond the amount required to raise the level thereof to bleeder 22 will drain out through the bleeder, after which plugs l4 and 23 are again secured tightly in place thereby sealing filler hole {3 and bleeder 22.

The air necessary for proper functioning of the recoil system is therefore trapped in expansion chamber [9, since it is largely above the level of bleeder 22 and the hydraulic fluid cannot run up into it to displace air therefrom above the level of bleeder 22, whereas had the chamber been installed on the lower side and the corresponding passages used for filling and bleeding, much or possibly even most of the chamber would have been filled with oil displacing the air therefrom since a larger proportion of the volume of the chamber would have been below the level of bleeder 22, and furthermore air would very likely have worked up into cylinder I.

In the position shown in Figs. 6 and 7, the position of the recuperator elements is shown for the approximate maximum tilting of the cannon. At this angle, expansion chamber is has approached so near the horizontal that fluid up to the level of bleeder 22 is beginning to extend out into the chamber l9 and fill an increased proportion thereof. Any further tilting will result in an increase in the amount of fluid that will be retained in chamber IS with a corresponding decrease in the amount of air entrapped thereby reducing the compressible properties.

When the fluid has reached its proper level in chamber I9 it will be noted that the socket I! having plug 20 assembled therein, has a minute amount of air entrapped therein as shown in Figs. and '7, but has no detrimental affect upon the functioning of the device.

Thus it is evident that the specific structure shown in the drawings is designed to permit tilting to approximately 60 each side of the normal vertical axis. If a greater tilting than 60 is likely to be encountered, then the angular displacement of the chamber l9 and bleeder 22 would have to be somewhat increased. Accordingly, it will be evident to those skilled in the art that although the layout shown is designed to meet the requirements of tilting up to a maximum of each side of the vertical, this limit can be easily increased by increasing the angular displacement or by provision of additional sockets.

With the firing of the cannon, heat is developed in the cylinder as a result of the Work done in absorbing the energy of recoil by the reciprocation therein of a piston (not shown). This results in expansion of the oil with a consequent reduction in volume of the air pocket. However, due to compressibility of the air trapped in expansion chamber I9, the pressure developed is comparatively slight with the result that the danger of forcing any of the buffer oil past the packings (not shown) is generally negligible. Any loss of oil under such conditions would result in a partial vacuum when the gun cooled and might lead to air then being drawn into the cylinder. In case this occured the presence of any appreciable volume of air within the cylinder would tend to reduce the resistance to motion of the piston, because of the lack of viscosity of air with the result that the hydraulic damping of the recoil stroke would be reduced and with increased volume of air within the cylinder would be virtually destroyed.

Although described in connection with an airplane cannon, it is to be distinctly understood that this specific application is illustrative only and in no way limits the scope of application of the invention.

It is therefore apparent that this invention provides a means for assuring that air will be trapped in the expansion chamber and not in the recoil cylinder, during filling or replenishing of the recuperator system.

I claim:

1. In a cannon recuperator having a hydraulic cylinder the improvement comprising, a top and bottom yoke mounted on the forward end of the cylinder, said top yoke having a pair of angularly disposed boss-like members in a plane perpendicular to the axis of the cylinder, each of said bosses being provided with a threaded recess opening rearwardly and inclined upwardly and a passageway therefrom communicating with the interior of the hydraulic cylinder, vent means near the upper end of each of said bosses communicating with said recess, an expansion chamber adapted to be threaded into said recess of one of said bosses, said passageway permitting hydraulic fluid to enter said chamber, and a plug threaded into said recess of said other boss for sealing said passageway, said vent means being provided for bleeding said chamber Whereby a limited amount of air may be trapped therein when the cylinder and part of said chamber are filled with hydraulic fluid.

2. In combination with a cannon recuperator having a hydraulic cylinder, 2. top and bottom yoke adapted to surround the cylinder, said top yoke having a plurality of sockets extending therefrom in a plane perpendicular to the axis of the cylinder, each of said sockets being provided with a threaded recess terminating in an opening therefrom to permit the passage of hydraulic fluid from the cylinder and vent means near the upper end of said socket communicating with said recess, an expansion chamber adapted to be selectively secured in said recess of any one of said sockets whereby said chamber is maintained in an elevated position above the cyl- REFERENCES CITED The following references are of record in the file of this patent:

6 UNITED STATES PATENTS Number Number Name Date Palmer July 6, 1909 FOREIGN PATENTS Country Date Great Britain Sept. 25, 1939 

